Transcriptome response to nitrogen starvation in rice.

Nitrogen is an essential mineral nutrient required for plant growth and development. Insufficient nitrogen (N) supply triggers extensive physiological and biochemical changes in plants. In this study, we used Affymetrix GeneChip rice genome arrays to analyse the dynamics of rice transcriptome under N starvation. N starvation induced or suppressed transcription of 3518 genes, representing 10.88 percent of the genome. These changes, mostly transient, affected various cellular metabolic pathways, including stress response, primary and secondary metabolism, molecular transport, regulatory process and organismal development. 462 or 13.1 percent transcripts for N starvation expressed similarly in root and shoot. Comparative analysis between rice and Arabidopsis identified 73 orthologous groups that responded to N starvation, demonstrated the existence of conserved N stress coupling mechanism among plants. Additional analysis of transcription profiles of microRNAs revealed differential expression of miR399 and miR530 under N starvation, suggesting their potential roles in plant nutrient homeostasis.